1. Field of the Invention
The invention relates to a rotary variable resistor of modular construction.
2. The Prior Art
A variable rotary resistor constructed in a modular design, such that several similar modules may be connected with each other, is already known. Each module consists of a pot-like housing with a front and a rear surface. In the housing, a spring carrier is rotatably supported by means of a shaft, with the shaft extending through a central opening of the housing. A contact spring is secured to the spring carrier and the contacts of the contact spring resiliently contact the resistance guide way and the collector guide way. The resistance guide way is fastened to a support plate forming a closure for the housing. The collector guide way is constructed in the form of a flat collector ring with central opening, and is located at the bottom of the pot-like housing, with the shaft protruding through the opening. The housing itself is connected by means of a locating plate with a threaded bushing flange.
Further, a variable rotary resistor with a pot-like housing, comprising a metal fastening bushing and a housing part of synthetic material equipped with resiliently-biased clamping jaws to hold the insulating support, is also known. The resistance guide way and the collector guide way are mounted with the associated connecting lugs, on the insulating support. Additionally, the spring carrier with its sliding contact is rotatingly supported in the insulating support. The rotary motion is transmitted from the actuating shaft to the spring carrier by means of a dog plate which engages a groove in the face of the actuating shaft and a helical recess in the spring carrier. The resistance part may thus be separated from the housing part easily and without being destroyed. Replacement is thus readily possible. A disadvantage of the device consists of the fact that the rotary resistor in the final analysis can be assembled from two standard parts only. This eliminates any possibility of further variations. Therefore, if changes are desired, for example concerning the connecting lugs, an entire new resistance part with altered connecting lugs must be manufactured. If a different resistance guide way is desired, then an entirely different resistance component must be manufactured. Thus, the fact that the rotating resistor may be assembled from only two standard parts, proves in the final analysis to be a disadvantage.